Yeah sounds like you need a new system. If you have tried different inputs and still dead the AMP is faulty or the sub is dead.
You should have a look at the software of your sound card. Is the upmix function enabled or did you choose the wrong speakers say: Headphones instead of 2.1 speakers. When the upmix function is enabled the device only works if you plug in 1 jack for all speakers. If it is disabled then you need to plug in all jacks.
Just took another peek at the settings, it's all pretty much set to default since day one of using these speakers. Also selected 2.1 speakers as the profile as well. The audio comes out of the two speakers just fine, it's just the boom that's missing. The subwoofer was working again out of nowhere for a day, but then it just went out again. So I thought it might be an issue with the aux cord, bought and replaced it with another cord but that didn't fix the issue either. I think you're right, the amp is faulty and it's time to look for another system!